Windows 1.0 Development Release #5 is a pre-release build of Windows 1.0. This build is the fifth in the Development Release series, intended to help application developers design and develop their applications to work with Windows. According to INSTALL.BAT, it was compiled on 1984-11-01. It is the earliest leaked build of Windows so far.

By default, this build is installed to C:\windows\test, with development resources in C:\windows\bin. Resources are stored in .res files outisde of the executables and will also open their associated program when double-clicked. The overall UI design philosophy was not finalized yet, which can be clearly seen in dialogs - some use a menu bar rather than OK and Cancel buttons. Also included are several mockup applications, namely Chart, Graph, PPDemo, Sample and Template, along with their source code.

7. Install DOS on the HDD (you can skip this step if you wish to use DOS bootdisk everytime)

7.1 Run sys C:

7.2 Run copy *.* C:\*.*

7.3 Eject the floppy (Disc -> Eject drive A:) and reboot

8. Install Microsoft Windows 1.0 Development Release #5

8.1 Insert the first floppy of your DR5 setup

8.2 Run copy A:\install.bat C:\

8.3 Run C:\install.bat

8.4 Confirm the 4 prompts, answer Yes to any question

8.5 After another confirmation, it should start copying from Disk 1 If you have the mouse captured, make sure to press CTRL+END while it's copying! Otherwise, the keypress would count as a command to continue!

Development Release 5 is still a rather early build and thus has some notable performance and stability issues. Prolonged or memory intensive use (e.g. running many applications at the same time) can cause the build to hang or crash without warning, sometimes to the point where only a hard reboot will restore functionality to the system.

Starting Notepad may cause the system to hang or crash if the configuration file USER.PRO is present in the \windows\test directory. You can work around this issue by either deleting, renaming or moving the file, but the better solution is to add these two lines to your CONFIG.SYS file:

If you try to access an empty floppy drive in MS-DOS Executive, the system will display a DOS disk error message over Windows and hang or crash. This was fixed in the Alpha release, so that Windows instead displays an error message.

This build supports both CGA (640x200) and Hercules (720x348) display modes, both in monochrome only. However, only CGA drivers are installed by default. Switching between them can be done with the included DRIVERS.BAT batch file, just follow these simple steps:

path C:\windows\bin
cd C:\windows\test
drivers DesiredDriver

Replace DesiredDriver with IBMCOLOR for CGA or with HERCULES for Hercules. Please note that you must of course also change the emulated display adapter when performing the switch.

Also in USER.PRO is a Run value in the [windows] section. Any executable you include in this space-separated list gets executed before the MS-DOS Executive starts. Applications started this way go directly into an iconic mode at the bottom of the screen (in other words, they'll be minimized).

This build contains a warning dialog saying "Windows is about to crash". It's very hard to trigger it though, as the system will usually either hang or crash completely before the message can be displayed.

MS-DOS Executive in this build actually support simple drag and drop operations for moving files between directories. This feature was later completely removed between the Alpha and Beta releases, when MS-DOS Executive received a minor redesign.

If you take a look at REMOVE.BAT (in the WINDOWS folder), you will see a much older date - 29/05/84. It is possible that this file was re-used from a previous build, probably from Development Release 1 which was released in 1984-05 according to InfoWorld 1984-05-07.[1]

Also, if you take a look at the installation procedure in INSTALL.BAT, you'll notice that it empties some folders, but completely removes \windows\lib. It's possible that previous releases used this folder, whereas DR5 uses just \lib instead. The batch file for uninstalling Windows, REMOVE.BAT, doesn't care about \windows\lib, but mentions \lib, so it was either modified, or the release from which it came already used \lib.

The only reference to any previous releases in the provided documentation, in QANDA.DOC (found in \windows\doc), where it says: "The RC.EXE program had a small file buffer. It simply couldn't handle your large menu. The bug has been repaired".

The documentation contains only one timestamp, and that is 16/10/1984 16:37 in GRAPH.DOC (also in \windows\doc). The files haven't been changed to have the same date, so you can clearly see when was each file created and modified.

In QANDA.DOC, an upcoming January release is mentioned several times: "By our January release, our goal is to..." and "In our January release, there will be...". Because the Alpha was released in 1985-01, this probably means no additional releases were made between DR5 and Alpha.

/* figure out how many "characters" can fit on a line and down the screen */
/* NOTE: this routine is very stupid. These two lines get executed only */
/* once, and if the size of the window changes, it does not adjust. */

Windows 1.0 introduced the icon and cursor format (.ICO and .CUR files), though it was changed in Windows 3.0 to what it still is today. The two formats are not compatible, but files can be converted from one to the other without much work.

SAMPLE.EXE's icon is the Superman logo.

A bomb icon exists in WINDOWS.RES, to be used for error messages, but neither Windows nor any included application ever display a true error message, only warnings, which feature the musical note icon instead. The error icon was later changed to a hand performing the "stop" gesture, but the original choice of a bomb indicates early Windows development was influenced by Apple's Macintosh, which also used a bomb as an error icon.

Also in WINDOWS.RES is an unused icon named TRASH, indicating older builds likely had a trash can feature of some kind. This is supported by photos and articles describing older builds, where this icon can be seen and is described as a place where files are discarded.[2] Clearly, the feature was already removed before DR5 with only the trash can icon remaining.